(Adds analyst comments, FERC commission changes)
Feb 3 (Reuters) - U.S. energy regulators late on Thursday approved construction of Energy Transfer Partners LP's Rover natural gas pipeline from Pennsylvania to Ontario, according to a filing made available on Friday.
The 3.25 billion cubic feet per day project is one of several awaiting decisions from the U.S. Federal Energy Regulatory Commission (FERC) while the agency still has a quorum and can make such rulings.
ETP has said it expected to put the first phase of the $4.2 billion project on line during the second quarter of 2017 and the remainder in service during the fourth quarter.
FERC leadership changes last week prompted several energy firms to request the agency make decisions this week on proposed gas pipelines to avoid potential construction delays.
President Donald Trump appointed Cheryl LaFleur as acting chair, which prompted Norman Bay, the former chairman, to announce he would step down on Feb. 3, leaving the commission without the quorum needed to conduct major business.
Other companies hoping for decisions this week include units of Spectra Energy Corp on the Nexus pipeline, Williams Cos Inc on Atlantic Sunrise, TransCanada Corp on Leach and National Fuel Gas Co on Northern Access.
Analysts at U.S. financial services firm Cowen and Co said on Friday the approval of construction of Rover was a positive for summer gas differentials in the Appalachia region.
The premium of gas at the Henry Hub GT-HH-IDX benchmark in Louisiana over the Dominion South E-DOMSP-IDX hub in southwest Pennsylvania's Marcellus Shale narrowed to a near three-month low on Thursday and put it within a penny of its lowest in two years.
Cowen said Energy Transfer can start cutting trees, which must be completed by March 31, but cannot build facilities until FERC staff is satisfied on the Stoneman House issue. Stoneman was a historic house in Ohio that the company demolished.
Cowen said the approval will benefit several companies that plan to ship gas on Rover, including Antero Resources Corp , Eclipse Resources Corp, EQT Corp, Gulfport Energy Corp, Rice Energy Inc, Range Resources Corp and Southwestern Energy Co.
Analysts at U.S. financial services firm FBR & Co said "failure to issue the Rover permit could have delayed the project by a year due to seasonal construction constraints."
FBR said FERC may consider Spectra's Nexus and NFG's Northern Access projects before Bay departs. But FERC has not yet issued any notices on Nexus or Northern Access. (Reporting by Scott DiSavino; editing by Chizu Nomiyama, G Crosse)